“…The deconvoluted C 1 s shows four peaks at 284.6, 286.5, 287.8 and 289.7 eV, corresponding to sp 2 carbon, sp 3 carbon, C–OH and O=C=OH or C=O, respectively. The presence of sp 3 carbon indicated a large amount of defects, which is well agreed with the Raman spectral analysis. Similarly, the observed four distinct peaks of O 1 s spectra (Figure (c)) at 531.7 eV, 530.3 eV, 533.2 eV and 534.7 eV reveals the presence of C=O quinone type groups, C–OH phenol groups and/or C–O–C groups, carbonyl groups in anhydrides or carboxyls, and chemisorbed oxygen and/or water, respectively.…”